4-vinyloxyazetidin-2-one, a novel substrate for β-lactam synthesis

Abstract

The present survey reports on the literature regarding the application of readily available 4-vinyloxyazetidin-2-one as a versatile building block in the synthesis of a variety of mono-, bi- and polycyclic β-lactams since its development in 1996. This novel substrate can be directly alkylated on the nitrogen atom of the β-lactam ring in contrast to commercially available 4-acyloxyazetidin-2-one. Moreover, subsequent cyclization via intramolecular nucleophilic substitution at C4 offers very efficient asymmetric induction, which in the case of the formation of 5-oxacephams is reversed relative to other known methods based on the condensation of 4-acetoxyazetidin-2-one with alcohols or [2 + 2] cycloaddition with chiral vinyl ethers. Particularly attractive are highly stereoselective approaches to 5-oxacephams and carbacephams which can be easily applied to solid-phase conditions.